1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member. More particularly, it relates to an electrophotographic photosensitive member comprising a photosensitive layer containing a barbituric acid derivative or thiobarbituric acid derivative having a specific structure.
2. Related Background Art
Inorganic photoconductive materials such as selenium, cadmium sulfide and zinc oxide have been hitherto used in electrophotographic photosensitive members.
On the other hand, electrophotographic photosensitive members comprised of an organic photoconductive material are known to include those comprised of a photoconductive polymer as typified by poly-N-vinylcarbazole or a low-molecular organic photoconductive material such as 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, and also those comprised of a combination of such an organic photoconductive material and a dye or pigment of various types.
The electrophotographic photosensitive members comprised of an organic photoconductive material have the advantages that they have good film forming properties so that they can be produced by coating, and much higher productivity so they can be provided at a low cost. They have also the advantages such that color sensitivity can be freely controlled by selecting sensitizers such as dyes or pigments used. Accordingly, studies have been hitherto made thereon over a wide range. Particularly in recent years, development of a function-separated photosensitive member comprising a lamination of a charge generation layer containing an organic photoconductive dye or pigment and a charge transport layer containing the above-mentioned photoconductive polymer or low-molecular organic photoconductive material has brought about remarkable improvements in the sensitivity and durability in respect of which the conventional organic electrophotographic photosensitive members have been considered to have disadvantages.
Materials that exhibit such photoconductivity are known to include, for example, azo pigments, and a barbituric acid derivative or thiobarbituric acid derivative as disclosed in Japanese Patent Application Laid-Open No. 57-119355.
Electrophotographic photosensitive members in which a conventional disazo pigment or a barbituric acid derivative or thiobarbituric acid derivative is used, however, are not satisfactory in view of sensitivity, and potential stability in repeated use. Thus, only a very few materials have been put into practical use.